Determining Electron's Momentum and Position Simultaneously

  • #1
lisathomas
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TL;DR Summary
Is it possible to retrospectively determine the position and speed of an electron at the same moment?
Hi. I am a high school science teacher (A&P, Chem, and Environ Bio & Eco) so my understanding is limited on subatomic particles...please forgive me if this is a really stupid idea.

I teach my chem students about electrons, orbitals, electrons' "address" using the four quantum numbers, 1s2 -1/2 spin. I use the example of an airplane's propellers or a fan's blades to explain that we can know how fast they are traveling or their exact position but not both at the same time. I was watching my fan in my bedroom this morning turning around and around and I would pick a blade and watch it then allow it to blur in with the rest as I watched all the blades turn at a slow speed. Then, I began to blink my eyes rapidly which allowed me to take "moment pictures" which allowed me to see the placement of each blade and the speed of my eyes opening and closing with the change in position of the blades allowed me to "measure" the speed. Is there some way we could do that in a lab with electrons?
 
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  • #2
An atom is a bound energy state of its constituent particles. The electrons do not have classical trajectories, in terms of position as a function of time; or, momentum as a function of time.

QM involves an entirely different description of nature, based on states and state vectors, as opposed to classical trajectories. The ceiling fan analogy doesn't apply, I'm sorry to say.
 
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Likes lisathomas
  • #3
Wow! Thank you for the clear explanation.
 
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Likes berkeman and weirdoguy
  • #4
Wish when I was in school I had a teacher curious enough to post this
 
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Likes lisathomas
  • #5
Oh, thank you! That is so kind.
 

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